Biogas and biomethane: Production route
Wet tanks, dry digesters and the upgrade to biomethane
What this tab covers How it is made: the main production routes or, for product families, the main product types and technologies, compared on share of supply, inputs per tonne, plant scale, yield, co-products and unit cost.Almost all biogas comes from anaerobic digestion; landfill gas capture is the other large source. Wet digesters suit manure, sewage and food waste; India's newer CBG plants use dry or high-solids digestion of paddy straw, press mud and Napier grass, which needs pre-treatment. Upgrading turns biogas into biomethane. Thermal gasification of wood or straw followed by methanation (bio-SNG) is technically proven but small.
Routes compared
| Route | Share of supply | Inputs per tonne | Typical scale | Yield | Co-products | Unit cost |
|---|---|---|---|---|---|---|
| Wet anaerobic digestion (manure, sewage, food waste) | majority of world biogas (indicative) | about 60-70 t fresh cattle dung per t of CBG (indicative, basis: about 35-40 m3 biogas per t dung) | Europe's average biomethane plant 483 m3 per hour; Indian dung plants 1-10 t CBG a day (indicative) | about 20-25 m3 methane per t dung; 100-150 m3 per t food waste (indicative) | digestate (liquid and solid fertiliser), CO2 from upgrading | IEA average biomethane cost about $36-108/MWh (about $10.5-32/MMBtu) |
| Dry and high-solids digestion of residues (paddy straw, press mud, Napier grass) | growing share of India's new plants (indicative) | about 8-10 t paddy straw, 20-25 t press mud or 25-30 t Napier grass per t CBG (indicative) | 10-30 t CBG a day; Adani TotalEnergies' Uttar Pradesh plant takes about 600 t of feed a day (BioEnergy Times) | about 100-150 kg CBG per t dry straw (indicative) | fermented organic manure (FOM) | capex about Rs 120-130 crore per plant (derived: Petronet-Gruner Rs 1,200 crore for 10 plants; Reliance Rs 65,000 crore for 500 plants) |
| Landfill gas capture | large in the US (indicative) | not applicable (waste already in place) | 1,000-10,000 m3 per hour (indicative) | falls over decades | none | cheapest RNG source (indicative) |
| Upgrading technologies | about 5.2 bcm upgraded in Europe (2024) | about 0.25-0.4 MWh electricity per 1,000 m3 raw biogas (indicative) | 100-5,000 m3 per hour | 97-99% methane recovery (indicative) | biogenic CO2 (food or e-fuel grade) | a few $ per MWh (indicative) |
How each route works
Wet anaerobic digestion (manure, sewage, food waste)Slurry of 5-15% solids is stirred in heated tanks; biogas is collected and upgraded or burned. Manure digesters capture methane that would otherwise leak from lagoons.
proven and carbon-negative with manure; small, dispersed feedstock
IEA Outlook for Biogas and Biomethane (May 2025), via World Biogas Association and BioCycle; European Biogas Association Statistical Report 2025, via Renewable Energy Magazine, 10 Dec 2025; indicative Dry and high-solids digestion of residues (paddy straw, press mud, Napier grass)Lignocellulosic feed is chopped and pre-treated, then digested with recirculated slurry. This is the main design for new Indian CBG plants by Reliance, Adani TotalEnergies and IOCL.
uses residues that are otherwise burned; seasonal supply and storage costs
BioEnergy Times, Aug 2026; BioEnergy Times Oct 2026 (Petronet); indicative Landfill gas captureWells and pipes in closed landfills collect gas, which is burned for power or upgraded to RNG. Large in the US.
low cost; captures only part of landfill methane
indicative Upgrading technologiesMembranes, water scrubbing, PSA and amine units separate CO2; cryogenic units make bio-LNG. Methane slip from upgrading ranges from 0.2% to 10% in Europe (IEA).
turns low-value gas into grid gas; slip must be controlled
IEA Outlook for Biogas and Biomethane (May 2025), via World Biogas Association and BioCycle; European Biogas Association Statistical Report 2025, via Renewable Energy Magazine, 10 Dec 2025 Unit economics are indicative ranges from the sources named; costs move with feedstock and energy prices, plant size and region.